package com.github.kezhenxu94.playground.leetcode;

/**
 * <pre>
 *
 * 419. Battleships in a Board
 *
 * Given an 2D board, count how many different battleships are in it. The 
 * battleships are represented with 'X's, empty slots are represented with
 * '.'s. You may assume the following rules:
 *
 * You receive a valid board, made of only battleships or empty slots.
 * Battleships can only be placed horizontally or vertically. In other words,
 * they can only be made of the shape 1xN (1 row, N columns) or Nx1 (N rows,
 * 1 column), where N can be of any size.
 *
 * At least one horizontal or vertical cell separates between two battleships
 * - there are no adjacent battleships.
 *
 * Example:
 *
 * X..X
 * ...X
 * ...X
 *
 * In the above board there are 2 battleships.
 *
 * Invalid Example:
 *
 * ...X
 * XXXX
 * ...X
 *
 * This is not a valid board - as battleships will always have a cell separating
 * between them.
 *
 * Your algorithm should not modify the value of the board.
 *
 * @author Ke Zhenxu
 */
public class Solution419BattleshipsInABoard {

	public int countBattleships(char[][] board) {
		int result = 0;
		for (int i = 0; i < board.length; i++) {
			for (int j = 0; j < board[i].length; j++) {
				if (board[i][j] == '.')
					continue;
				if (i > 0 && board[i - 1][j] == 'X')
					continue;
				if (j > 0 && board[i][j - 1] == 'X')
					continue;
				result++;
			}
		}
		return result;
	}
}
